Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Groovy Concentric Background 3
Source GDJ
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Psychedelic Geometric Background No Black
Source GDJ
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Non-seamless pattern drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
Prismatic Triangular Background Design Mark II 5
Source GDJ
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
The edges of all the red objects line up either vertically or horizontally, but it doesn't appear so. Made from a square tile that can be got by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Sort of reminds me of those old house wallpapers.
Source Tish
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
A bit simplified version. Although it could be edited out to be simpler. Anyway, this time the tiling is converted to a pattern fill -which is using clipping for the tile's edges.
Source Lazur URH
A free light orange brown wallpaper with vertical stripes designed for use as a tiled background on websites. An yet another background pattern with vertical stripes.
Source V. Hartikainen
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
From a drawing in 'Hundert Jahre in Wort und Bild', S. Stefan, 1899.
Source Firkin
Embossed lines and squares with subtle highlights.
Source Alex Parker
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin